Hi Chris, The encoder datasheet gives a voltage range of 10-30vdc so I don’t think direct connection with 5vdc would be an option.
Would a direct connection via voltage dividers eliminate the ‘ghost pulses’ being picked up by the Pico board? The encoder won’t be running above 3,000 rpm. Pete > On 10 Oct 2021, at 19:00, Chris Albertson <albertson.ch...@gmail.com> wrote: > > Is your math right? Yes, I get 83 KHz for a 500 line encoder at 10,000 > RPM. Yes that is < 1% of the isolator's rated speed (of 10 MHz) > > But the schematic had an RC low pass filter in the encoder output that > would have prevented the system from working above about 1000 RPM. I see > this is gone now. > > But why are these isolators even needed? Why not simply operate the > encoder at 5 volts? > > Or if you must run the encoder at 12 volts, you can do level translation > with a resistor voltage divider. > > There is nothing yo isolate. The entire system runs on a common ground and > there is no high power devices in the schematic and I assume the entire > system is in one building with no long (100 meter) cables > > If you are worried about accidents blowing up the controller, use diodes to > shunt any transients. But really there are no inductive loads > > > > > > On Sun, Oct 10, 2021 at 10:25 AM John Dammeyer <jo...@autoartisans.com> > wrote: > >>> From: Gene Heskett [mailto:ghesk...@shentel.net] >> >> >> >>> If the opto's are fast enough, you should be >>> fixed. A 500 ppr encoder s/b fine. A 1024 or 1000 requires a faster >>> opto. >>> >> >> HI Gene, >> Comparing the cheap far east BoB optos with the HCPL2621 is apples and >> oranges. >> >> A 2500 line encoder still only creates 2500 pulses. The quadrature just >> looks at two lines and 2 edges for 10,000 edges. But the max speed of his >> encoder is 10,000 RPM which in RPS is 166.7 and would result in 417kHz >> which is 4% of the opto max 10 Mbps capabilities if the encoder was 2500 >> line. >> >> But his is 500 line so at 166.7 RPS is 83kHz which is 0.8% of opto >> capabilities. >> >> >> John >> >> >> >> >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
